Murat Tozlu

Cortical bone thickness of the alveolar process measured with cone-beam computed tomography in patients with different facial types.

INTRODUCTION The purpose of this study was to determine the cortical bone thickness of the alveolar process in the maxilla and the mandible on cone-beam computed tomographs of adults with low, normal, and increased facial heights. METHODS This study was conducted on 155 images of adult patients (20-45 years old) who were assigned to the low-angle, normal, and high-angle groups. The thickness of the buccal cortical plates of the maxilla and the mandible, and the palatal cortical plates of the maxilla, were measured. RESULTS There was no statistically significant difference between the groups regarding mean ages, sex, and sagittal facial types. High-angle patients had significantly lower values than did low-angle patients in all mini-implant insertion sites in both the maxillary and mandibular alveolar bones. The mandibular and maxillary buccal measurements showed a similar pattern; the lowest values were for the high-angle group, followed by the normal group; the highest values were measured in the low-angle patients. CONCLUSIONS Clinicians should be aware of the probability of thin cortical bone plates and the risk of mini-implant failures at maxillary buccal alveolar mini-implant sites in high-angle patients, and at mandibular buccal alveolar mini-implant sites between the canine and the first premolar in normal and high-angle patients.

Debonding of ceramic brackets by a new scanning laser method

INTRODUCTION The purpose of this in-vitro study was to develop a new method to debond ceramic brackets by scanning with an Er:YAG laser. METHODS Sixty bovine mandibular incisors were randomly divided into 2 groups of 30. Polycrystalline ceramic brackets were placed on their labial surfaces by using the orthodontic composite adhesive Transbond XT (3M Unitek, Monrovia, Calif) and light cured for a total of 40 seconds. The first group was the control group, with no laser application performed. The Er:YAG laser was used on each bracket in the study group at 4.2 W for 9 seconds with the scanning method. The force required for debonding the brackets was applied 45 seconds after laser exposure. Shear bond strengths were measured in megapascals with a universal testing machine, and adhesive remnant index scores were assigned to each specimen. RESULTS Statistically significant (P <0.001) lower shear bond strengths were found in the laser group (9.52 MPa) compared with the control group (20.75 MPa). Likewise, the adhesive remnant index scores were statistically different (P <0.001); the laser group had twice as many samples with adhesive, with the adhesive remnant index scores of 2 or 3. CONCLUSIONS The application of the Er:YAG laser with the scanning method is effective for debonding ceramic brackets by degrading the adhesive through thermal softening.

Quantitative evaluation of alveolar cortical bone density in adults with different vertical facial types using cone-beam computed tomography

Objective The purpose of this study was to quantitatively evaluate the cortical bone densities of the maxillary and mandibular alveolar processes in adults with different vertical facial types using cone-beam computed tomography (CBCT) images. Methods CBCT images (n = 142) of adult patients (20-45 years) were classified into hypodivergent, normodivergent, and hyperdivergent groups on the basis of linear and angular S-N/Go-Me measurements. The cortical bone densities (in Hounsfield units) at maxillary and mandibular interdental sites from the distal aspect of the canine to the mesial aspect of the second molar were measured on the images. Results On the maxillary buccal side, female subjects in the hyperdivergent group showed significantly decreased bone density, while in the posterior region, male subjects in the hyperdivergent group displayed significantly decreased bone density when compared with corresponding subjects in the other groups (p<0.001). Furthermore, the subjects in the hyperdivergent group had significantly lower bone densities on the mandibular buccal side than hypodivergent subjects. The maxillary palatal bone density did not differ significantly among groups, but female subjects showed significantly denser palatal cortical bone. No significant difference in bone density was found between the palatal and buccal sides in the maxillary premolar region. Overall, the palatal cortical bone was denser anteriorly and buccal cortical bone was denser posteriorly. Conclusion Adults with the hyperdivergent facial type tend to have less-dense buccal cortical bone in the maxillary and mandibular alveolar processes. Clinicians should be aware of the variability of cortical bone densities at mini-implant placement sites.

Pulpal Thermal Changes following Er-YAG Laser Debonding of Ceramic Brackets

Lasers are effective in debonding ceramic brackets. Unfortunately, while reducing the adhesive bond strength, lasers are also reported to increase pulpal temperature. The aim of this study was to evaluate the shear bond strengths and temperature increase levels after debonding ceramic brackets using an Er-YAG laser with or without water-cooling. Sixty polycrystalline upper premolar ceramic brackets were placed on the labial surface of sixty human premolar teeth which were randomly divided into three groups of twenty. A laser pulse at 5 W for 9 seconds was delivered to each bracket in both study groups either with water-cooling (water group) or without water-cooling (waterless group) using an Er-YAG laser. Debonding was performed 45 seconds after laser exposure and shear bond strengths were measured. Data comparison revealed a statistically significant difference between the groups. Mean temperature increases of 2.41°C and 4.59°C were recorded for the water and waterless laser groups, respectively. The shear bond strength value for the control group was 22.76 MPa and 10.46 and 6.36 MPa for the water and waterless laser groups, respectively. The application of Er-YAG laser with water-cooling was an efficient and safe method of debonding ceramic brackets.

Effects of a newly designed apparatus on orthodontic skeletal anchorage

Objective: An appliance was designed to increase the cortical bone surface contact area of miniscrew implants (MSIs). The purpose of this in vitro study was to evaluate the effects of this appliance on the anchorage force resistance and the stability of orthodontic MSIs. Materials and Methods: A total of 48 MSIs were placed into bone specimens prepared from the ilium of bovines. Half were placed with the newly designed apparatus and half were placed conventionally. All the specimens were subjected to tangential force loading perpendicular to the MSI with lateral displacement of 0.6 mm, using an Instron Universal Testing machine. The maximum removal torque of each tested specimen was also recorded. Both study and control groups were divided into two subgroups based on whether they had thin and thick cortical bone. Results: The test group had statistically higher force anchorage resistance and maximum insertion torque values than the control group (P < 0.001). The results were found to be more significant in cases in which the cortical bone was thin (P < 0.001). Conclusions: Within the limits of this in vitro study, the present findings suggest that the newly designed apparatus might have a favorable effect on MSI stability in patients presenting with thin cortical bone. Clinical studies are necessary to confirm the results that were observed in vitro.

Maxillary buccal cortical plate inclination at mini-screw insertion sites

OBJECTIVE To evaluate whether buccal cortical bone inclination varies for the maxillary alveolar processes of adult patients with decreased, normal, and increased facial heights. MATERIALS AND METHODS Cone-beam computed tomography images of 135 adult patients, including 49 hypodivergent subjects (26 women, 23 men), 40 hyperdivergent subjects (24 women, 16 men), and 46 normodivergent (25 women, 21 men) were analyzed. Cortical bone inclination measurements were made relative to the occlusal plane. Cross-sectional slices of the maxilla were taken at interdental sites from the distal aspect of maxillary canine to the mesial aspect of maxillary second molar. RESULTS Analysis of variance indicated significant differences (P < .05) between the angles formed by the line tangent to the cortical bone and the occlusal plane among the vertical facial types for the regions between canine and first premolar and between second premolar and first molar at miniscrew insertion sites. CONCLUSION The results of this study indicate that vertical facial pattern should be taken into consideration when adjusting the insertion angle of miniscrews at the maxillary buccal region.

Mini-İmplantların Devrilmesini Önlemede Yeni Bir Yaklaşım

OZET Amac: Calismanin amaci, ortodontik yuk altinda mini-implant deplasman miktarini belirlemek ve mini-implantlarin yaka kismina yerlestirilen yeni tasarlanmis bir aparatin (mini-implant ring - MIR) etkinligini degerlenmektir. Gerecler ve Yontem: Toplam 48 mini-implant sigir kalca kemiginden elde edilen orneklere uygulanmistir. Calisma grubunda 24 mini-implant MIR ile uygulanmis ve kalan mini-implantlar MIR olmadan uygulanarak kontrol olarak ayrilmistir. Tum mini-implantlar vida uzun eksenine dik olacak sekilde 200 g teget yuke tabi tutulmuslar ve vidalarin yer degistirmesi Instron Universal Test Makinesi kullanilarak milimetre cinsinden olculmustur. Yukleme testi sonrasi, her bir mini-implant cikarilmis ve kortikal kemik orneklerinin kalinliklari olculmustur. Orneklerin kortikal kalinligina gore, calisma ve kontrol gruplari, ince ve kalin kortikal kemik olarak alt gruplara ayrilmistir. Bulgular: 200 g kuvvet uygulandiginda, MIR ile uygulanan mini-implantlarin ortalama deplasman degerleri MIR olmadan uyg...

Three-dimensional evaluation of alveolar bone thickness of mandibular anterior teeth in different dentofacial types

Aim: The aim of this randomized study was to compare the alveolar bone thickness (ABT) of the mandibular incisor teeth of dental and skeletal Class I, II, and III adult patients at labial and lingual aspects of the bone and develop recommendations for the associated movements of teeth in this region, taking vertical facial type into consideration. Material and Methods: Sixty-two Class I, 74 Class II, and 63 Class III patients - aged between 20 and 45 - were assigned to three subgroups – high (H), low (L), and normal (N) growth patterns. On the axial slices of computerized tomographies, the measurements for the ABT on labial and lingual sides of the mandibular incisors were carried out at three levels. Results: In Class I group, at apex region, ABT of subgroups N and L were greater than H, at labial side. In Class II, ABT of subgroups N and L were greater than H, at apex at both sides and cervical lingual region. Similarly, ABT of subgroup L of Class III group was greater than H, at labial and lingual apex, mid-root regions. In Class II, the ABT of subgroup H was greater than L, at lingual cementoenamel junction. Conclusions: ABT of mandibular incisors of Class I patients is not affected from vertical pattern except for apical region. There is not a thick bone on the lingual side of the Class II, high-angle patients. The ABT of the Class III, high-angle patients is thin as a risk factor for proclination.

Evaluation of buccolingual molar inclinations among different vertical facial types

Objective The aim of this study was to compare the buccolingual inclination of maxillary and mandibular molars in adults with different vertical facial types. Methods Cone-beam computed tomography images of 135 adult patients (age, 20–45 years) with skeletal Class I maxillomandibular relationships were assigned to normodivergent (n = 46), hypodivergent (n = 49), and hyperdivergent groups (n = 40) according to linear and angular sella-nasion/gonion-menton measurements. The normodivergent group consisted of 24 females and 22 males, hypodivergent group of 26 females and 23 males, and hyperdivergent group of 24 females and 16 males. Buccolingual inclination of the maxillary and mandibular first and second molars was measured relative to the occlusal plane. One-way analysis of variance was used for intergroup comparison. Gender differences were evaluated using independent t-tests. Results Buccolingual molar inclinations did not differ significantly between females and males (p > 0.05). There were no statistically significant differences among the buccolingual inclinations of the first and second maxillary and mandibular molars of the groups (p > 0.05). Conclusions Buccolingual inclinations of maxillary and mandibular molars are similar in normodivergent, hyperdivergent, and hypodivergent adults with Class I sagittal relationships.

Treatment of a Class II Case with Palatally Inserted Distalization Mechanics in an Epilepsy Patient

This case report describes the protocol employed in the treatment of a patient with Class II malocclusion with mechanics including palatally positioned miniscrews. Treatment included the distalization of maxillary posterior teeth with mechanics including 2 miniscrews positioned on the palatal side. After a certain amount of distalization was achieved, the maxillary arch was bonded with Roth prescription brackets while the appliance was still active. When leveling of the upper arch was finished, the appliance was kept in the mouth as a retention device while the mandibular arch was bonded to continue treatment, which lasted for a total of 15.5 months. Mandibular and maxillary fixed retainers were placed at the end of active treatment. Pretreatment and post-treatment records revealed that vertical and sagittal skeletal cephalometric findings were not affected. Miniscrew anchorage used during distalization is an effective non-extraction treatment option for dental Class II malocclusion correction.